High-tech weapons used in war to save citrus industry

Eric Rohrig, a scientist with the Florida Department of Agriculture and Consumer Services, talks about a trap designed to capture Asian citrus psyllids on Jan. 27 during the Florida Citrus Show at the Havert L. Fenn Center in Fort Pierce. The Asian citrus psyllid, which spreads citrus greening, has been a serious problem for citrus growers. The 3D printed traps catch psyllids for testing, which could lead to a cure. (MOLLY BARTELS/TREASURE COAST NEWSPAPERS)

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Published on: 2/5/2016

Eric Rohrig held up a small cylindrical device that, at first glance, looked sort of like a spaceship. Or maybe like a creature that would pilot the ship.

Yellow tendrils snaked toward a round, perforated top. But this wasn't something Sigourney Weaver might have tried to kill in "Alien." It was, rather, a trap for something far more insidious, and far more destructive.

Rohrig, a scientist with the Florida Department of Agriculture and Consumer Services, had created the trap with a 3D printer. It was one of two prototypes he displayed at last month's Florida Citrus Show in Fort Pierce, designed to catch the citrus industry's greatest enemy — the Asian psyllid, the tiny bug that has spread the catastrophic "greening" disease to so many trees, decimating the industry.

"We tried different colors — yellow performs the best," said Rohrig, meaning the bugs find it more attractive.

He and other researchers also have tinkered with a variety of designs, churning out a series of prototypes via the 3D printer, which was purchased with funds from a National Institute of Food and Agriculture grant.

The idea isn't to catch every psyllid, but to catch some of them for testing — which could help lead to a greening cure. And already, Rohrig said, there are indications the engineered traps can catch more bugs than the standard yellow sticky traps now in use.

Score one for high-tech. And the industry's desperately hoping there's more where that came from.

The search for a greening cure was on everyone's mind at the citrus show. Some "solutions" touted by vendors were decidedly low-tech — for example, a company called Southern Citrus Nurseries was selling the "Tree Defender," basically a mesh bag that's tied around young trees to keep the bugs off. The University of Florida's Institute of Food and Agricultural Sciences was touting what amounts to a larger version of this, "screenhouses" where citrus trees are grown in pots inside a mesh structure. Early results are positive, though you have to wonder how viable a solution this is for growers whose trees are spread out over thousands of acres.

But it was the high-tech "solutions" that were the most intriguing, and seemed to hold out the most promise.

Scientists are now using nanotechnology — the manipulation of matter on an atomic, molecular and supermolecular scale — to attack the greening disease on the smallest of battlefields.

Swadeshmukul Santra, an associate professor at the University of Central Florida's Nanoscience Technology Center, has developed a bactericide — used to kill bacteria — derived from zinc.

Bactericides have been used successfully for decades to fight bacterial infections on pear and apple trees, and citrus growers have asked federal and state regulators to let them use substances on citrus trees. But Santra's zinc-based product is different, tinier.

Existing bactericide sprays coat the outside of a plant. Zinkicide particles are small enough to get into the plant and travel to the susceptible vascular tissue called the phloem, where the greening bacteria sets up shop.

The Zinkicide zaps the bacteria (you can tell I didn't major in chemistry), then is designed to break down and be metabolized out of the plant.

It will be several years before testing is complete and the product hits the market, if it gets that far.

Other bactericides are already in use.

Then there's lasers. Where's Sigourney Weaver when you need her?

Researchers at the University of Florida have discovered that using the devices can improve the success of antibiotic treatments. A laser beam is used to create tiny indentations on a citrus leaf — sometimes as small as a single cell layer deep — and then the antibiotic is applied, so that it comes into direct contact with infected tissue.

And one of the more promising "solutions" could wind up being the most controversial. You might have heard the term "genetically modified organism," or GMO. Late last year, researchers with The University of Florida's Institute of Food and Agricultural Sciences announced they had developed a genetically modified citrus tree that was better able to resist greening.

A recent survey by Florida Grower magazine found nearly two-thirds of respondents said GMO trees could be among the most immediate and effective solutions to greening. But the manipulation of genetic material in living organisms — in food — troubles many who worry about the health and environmental impact of GMOs.

People in the industry hope technological breakthroughs can save citrus from greening. Problem is, the breakthroughs, the testing and the process of bringing it all to market takes time, said Tom Jerkins, president of Premier Citrus in Vero Beach, one of the state's largest growers.

Time is one thing the industry is running out of.

"It's definitely a race against the disease clock, and the disease may drive too many growers out of business before really effective commercial solutions are available," said Jerkins.

"We're pleased with most of the progress, but frustrated it's not faster."